For computer tomograph examinations, a desired examination region of a body which is to be examined is usually found and selected by producing a general scan—also called a topogram. The topogram is a parallel or central projection of the body which reproduces the anatomic structure of the body. On the basis of the topogram, it is possible to stipulate a start and end point for, by way of example, layered scanning of the desired examination region.
For computer tomograph examinations, an X-ray detector unit in an X-ray computer tomograph is normally rotated about a system axis. When recording the topogram, on the other hand, the X-ray detector unit is static relative to the system axis, with the body being moved along the system axis when the topogram data record is recorded.
The topogram opens up the option of simple anatomic orientation. Although the topogram is not provided for diagnostic purposes, it would be desirable for certain areas of application if the topogram had diagnostic image quality. By way of example, it would be desirable when examining an emergency patient if the topogram could be taken as a basis for performing early diagnosis of any fractures, particularly of the spine, and internal injuries. This would render superfluous firstly early assessment of the patient's state of health, and secondly conventional X-ray scans. It would be possible, inter alia, to significantly reduce a dosage for the patient which is conditional on multiple X-ray examinations.